"I'm secure enough to where if I'm not having fun playing and feel like it's a struggle physically, then I won't continue to do it full-time."

Toms will certainly have enjoyed his first round as he looked to regain the title he won in 2003.

"It does feel good to play solid golf again," said Toms.

"It gives me a little bit of confidence. I hit a lot of great shots today, so it wasn't like it was a fluke round.

"If I hit my driver better, I could have had a great round, because I hit a lot of great iron shots."

Phil Mickelson and Jason Bohn are hot on the heels of Toms after opening rounds of 68, while Zach Johnson heads an eight-strong pack who are a shot further back.

Fiji's Vijay Singh fired a two-under 70, while Sergio Garcia, Jesper Parnevik and Ian Poulter share the honour as the leading Europeans on one-under.